1. Field of the Invention
The present invention relates in general to a control apparatus for a vehicular drive system, and more particularly to techniques for reducing or eliminating a risk of an adverse influence of an abnormal shifting action on the durability of the vehicular drive system.
2. Discussion of Prior Art
There is known a control apparatus for a drive system of a hybrid vehicle including a continuously-variable transmission having an electric motor, and a step-variable transmission connected to the continuously-variable transmission, which control apparatus is configured to control an operating state of the electric motor for continuously changing an input speed of the step-variable transmission while the step-variable transmission is placed in a selected one of gear positions, so that an overall speed ratio of the hybrid vehicle drive system is variable over a wide range. JP-2005-240891A discloses an example of this type of control apparatus.
According to the control apparatus disclosed in the above-identified publication is arranged such that the input speed of the step-variable transmission is determined by the operating speed of the electric motor and the operating speed of an internal combustion engine connected to the continuously-variable transmission, in other words, the operating speed of the electric motor changes with a change of the operating speed of the input speed of the step-variable transmission. Accordingly, an abnormal shifting action of the step-variable transmission due to some abnormality thereof causes an abnormal input speed of the step-variable transmission, which in turn gives rise to a risk of an abnormal operating speed of the electric motor, resulting in an adverse influence on the durability of the electric motor.